Effects Of Supplementation Of Montmorillonite And Yeast Cell Wall Into The High-Concentrate Diet On Lipopolysaccharide Adsorption,Nutrient Apparent Digestibility, Growth Performance And Selective Feed Ingestion In Beef Cattle

Rumen acidosis is common disease in ruminant production. In practical production, the beef cattle is frequently fed diets containing low proportions of forage because of the regional and seasonal lack of forages (especially the quality ones) and high proportions of concentrate (particularly grain) to meet the energy need of beef cattle. As a result, ruminal pH decreased and the microbial ecology was altered. When rumen pH is lower than the normal level, ruminal acidosis can occur, and a large amount of histamine, tyramine and endotoxin (LPS) will be released in the rumen and the lower gut. High concentrations of LPS can be translocated into the bloodstream across epithelium of the digestive tract, which subsequently elicits immunological responses and metabolic changes. As a result, the growth performance of cattle may be adversely affected. Therefore, reducing LPS release in the digestive tract and translocation across epithelium could minimize the adverse effects of LPS in animals. Montmorillonite (MMT) and yeast cell wall (YCW) are widely-used inorganic and organic adsorbent additives in animal feed. However, whether both of them can effectively bind LPS respectively in vitro remains unclear. Whether adding both of them into the diet of beef cattle can bind the LPS released in the digestive trac needed in vivo test to further explore. Therefore, at first we carried out an in vitro study on the effects of MMT and YCW on the adsorption of LPS, then further investigated the effects of dietary supplementation of MMT and YCW on LPS adsorption and translocation in the digestive tract, as well as on nutrient apparent digestibility, growth performance and selective feed ingestion in beef steers.Trial1:This experiment was conducted to study the effects of MMT and YCW on the adsorption of LPS in vitro. When the test simulated rumen physiological conditions in vitro (pH=5,T=39.5℃), the titers, the adsorption rates and the desorption rates of MMT and YCW binding the free LPS in rumen fluid and deionized water of containing exogenous LPS were measured respectively after incubation for1h and3h (early and mid of ruminant). The results showed:(1) Incubating for1h and3h, the LPS adsorption rates of MMT for rumen fluid of beef cattle reached22.01%and17.64%, respectively, and the titers were445.18EU/mg and367.89EU/mg; the LPS adsorption rates of MMT for deionized water of containing exogenous LPS were up to85.99%and69.69%.(2) Under the same incubation times, the LPS adsorption rates of YCW for the same rumen fluid reached16.28%and24.28%, respectively, and the titers were332.47EU/mg and506.32EU/mg; the LPS adsorption rates of YCW for the same deionized water were up to83.51%and85.16%.(3) The desorption rate of YCW showed a more stable state (P>0.05) in the whole test. In addition, the LPS adsorption rates and titers of YCW for both fluid were higher than MMT in the process of3h incubation.Trial2:This experiment was further investigated the effects of supplementation of MMT and YCW into the high-concentrate diet on LPS adsorption and translocation in the digestive tract, as well as on nutrient apparent digestibility and growth performance in beef cattle. Eighteen beef steers (Simmental x Luxi) with an initial body weight (BW) of335±7.5kg and similar body condition were randomly and evenly assigned to one of3experimental treatments for a50day trial in a completely randomized design. The first10days was a preliminary trial when all animals were fed a conventional diet. The experimental treatments consisted of the basal diets with addition on dry matter (DM) basis of1) nothing (control),2)2g/kg MMT or3)2g/kg YCW. The results showed:(1) Compared with control, dietary MMT supplementation decreased (P<0.05) LPS concentrations in plasma, feces, and the digesta of different sectors of the gastrointestinal tract except the cecum. Dietary YCW supplementation decreased (P<0.05) LPS concentrations in plasma, feces, and the digesta of the lower gut including the ileum, cecum and colon. In addition, dietary MMT and YCW supplementation both decreased (P<0.05) the levels of plasma APP.(2) Compared with control, dietary supplementation of YCW increased (P<0.05) acid detergent fiber (ADF) and total phosphorus (TP) apparent digestibilities. In addition, dietary supplementation of YCW increased (P<0.05) verage daily gain (ADG) and dietary supplementation of MMT tended to increase ADG (P>0.05); dietary supplementation of YCW and MMT improved feed efficiency (P<0.05).(3) Overall, YCM supplementation displayed a better effect than MMT supplementation in improving growth performance in beef steers.Trial3:This experiment was conducted to study the effects of supplementation of MMT and YCW into the high-concentrate diet on selective feed ingestion in beef cattle. Six beef steers (Simmental x Luxi) with an initial BW of331±6.3kg and similar body condition were randomly and evenly assigned to lap feed, each ring1to repeat. Each ring were fed three kinds of dietary A, B and C, including dietary A was based diet; dietary B was basal diet+0.2%MMT; dietary C was basal diet+0.2%YCW. The results showed:(1) During the transition period (3-4d), dietary MMT and YCW supplementation both decreased (P<0.05) average daily matter intake (ADMI) and the percentages of daily feeding times in beef cattle.(2) After the transition period, dietary MMT supplementation was not significant effect (P>0.05) on ADMI and the percentages of daily feeding times in beef cattle, while dietary YCW supplementation showed a gradually increasing trend.In summary, in vitro tests in rumen fluid and in vivo trials in beef steers for the adsorption of free LPS were carried out, which showed that MMT and YCW had good adsorption effects. In addition, dietary YCW supplementation increased ADF and TP apparent digestibilities, enhanced ADG and improved feed efficiency; dietary MMT supplementation tended to enhance ADG, and significantly improved feed efficiency. Although MMT and YCW may contain unique smell or taste and significantly affect on selective feed ingestion in beef cattle during the transition period (3-4d), dietary MMT supplementation was not significant effect on ADMI and the percentages of daily feeding times after the transition period, while dietary YCW supplementation showed a gradually increasing trend in beef cattle. Therefore, in practical production of ruminants, diatery supplementation of MMT and YCW can be used as a new method for adsorption of free LPS in vivo.